head = [3, 2, 0, -4], pos = 1


// var hasCycle = function (head) {
//     let slow = head
//     let fast = head
//     while (fast && fast.next) {
//         slow = slow.next
//         fast = fast.next.next
//         if (slow === fast) {
//             return true
//         }
//     }
//     return false;
// };

var hasCycle = function (head) {
    let slow = head;
    let fast = head;

    while (fast && fast.next) {
        slow = slow.next;
        fast = fast.next.next;
        if (slow === fast) {
            return true;
        }
    }
    return false;
}

console.log(hasCycle(head));
